The matter of unwillingness to train spans all professions. Everyone wants you to have prior experience, and no-one is willing to give experience number one, unless you're willing to spend years at an unpaid internship, as one or two semesters doesn't cut it anymore (and still have to wade through hordes of others fighting to be slaves)

okay, now i'm injecting my bitterness in here. Excuse me

Because increased skilled labourers increase the number of jobs available - both skilled and unskilled.

Clarify context you mean that, as if you mean a company hiring skilled labor will demand more labor, or do you mean the economy on the whole, because hiring skilled labor means that one person gets a normally higher paying job and that means they have increased demands put on the economy, which generates activity that requires increased hiring?  Second, post some evidence to back up your claim.  

http://news.cnet.com/8301-1001_3-57473046-92/tech-layoffs-hit-3-year-high-of-51529-in-first-half-of-2012/

The first half of 2012 showed that layoffs are at a 3 year high. The high tech industry apparently has too much manpower.

Highly Skilled labor is the root of productivity, since they're the kinds that invent new products and increase productivity on existing ones, and thus make room for the business to expand and hire semi-skilled or unskilled labor, as well as peripheral employees (from human resources to janitors and everything in between)

I would prefer to have them work here and pay taxes than for the company to open a branch in another country.

I understand the bitterness, but the thing that bothers me about not training is that the companies that  hire junior people tend to be better off for it ...

When companies hire senior people to do work that should be handed off to junior team members their employees tend to get bored pretty quckly, under-perform, and then leave for greener pastures.  If there is a healthier balance between junior, intermediate and senior employees everyone has work that is at an appropriate challenge level, career development is a fairly organic process, and everyone is happier.

Education is just another form of capital. The more of it you have, the greater the productivity of the economy, wages rise, and thus so does everything else.

But, immigrants are slightly different from just normal trained citizens. Why? Because they're risk takers. Somebody who is going to risk everything to move to another country, is much more likely to risk everything in starting a business, or investing a large sum of money. It's not surprising that a large chunk of businesses, large and small, have their roots in migrant labour.

And, I'm not going to post evidence, no point. A simple Google search will provide thousands of articles, studies, and what-have-you disputing and agreeing with my point, so it proves nothing.

It really all depends on what you're expecting when you first enter the labour force. There are so many graduate schemes, entry level jobs, apprenticeships, etc., out there.

I just think that so many people have an unrealistic expectation of what work is going to be like. So many people on my course (Computer Science) believe that they will be able to walk out, and pick up a high-paying job in the Fortune 500, or some kind of job at Naughty Dog, or something. When they don't get the jobs that they wanted immediately, they hold out, pass up some real sloggish work, and then try to get in the game a few years down the line, when they're completely out-competed.

I've managed to get a job developing technology for HSBC in Hong Kong for 12 months. The money isn't fantastic, and I've literally had to move half way around the world, but I will now already have a year's worth of experience once I've finished my degree. Take one or two graduate placements, perhaps one in the UK, one in the US, and I would have clocked up a couple of years experience, for multiple companies, in multiple countries.

Work a career ladder for 10-15 years, and then leave and start my own business.